The invention concerns a stabilized, aqueous, alkaline gold bath, containing a dicyanogold (I)-complex, a complex former, a reducing agent, and customary additives, for the electro-less deposition of gold onto gold and metals that are more electro-negative than gold, as well as alloys of these metals.
Gold baths for the electro-less deposition of gold, i.e. deposition without the use of electrical current, are already known. These are alkaline or acid gold baths which mostly contain an alkali-dicyanoaurate (I), a complex-former, a reducing agent, as well as additives for controlling the velocity of deposition and for improving the adhesive strength of the deposited layer of gold on the substrate. (See, e.g. United States Pat. Nos. 4,091,128; 3,300,328; 4,154,877; 3,032,436; German Offenlegungshriften DE-OS Nos. 2,052,787; and 2,518,559.) However, all of these baths display, as a rule, unsatisfactory stability, decomposing during the deposition of metallic gold.
In addition, the mentioned gold baths are suitable only for the gold-plating of metals which are more electro-negative than gold. Accordingly, an optimal electro-less deposition of gold onto gold is not possible using these known gold baths.